क्षोभमंडल (ट्रोपोस्फीयर) में निम्नलिखित में से कौन सा एक द्वितीयक प्रदूषक है?

Prolonged exposure to extreme cold temperatures may result in tissue damage known as frostbite, which is categorized as a:

In the context of ecosystem energy dynamics, which of the following expressions correctly defines Net Primary Productivity (NPP)?